Unlike low fuel and tire pressure warnings, the "check engine" light can mean several different things are wrong with your vehicle, some of them much more critical than others and very expensive to fix. But what is it most likely to be?

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According to the latest study by CarMD of 15.9 million "check engine" repairs in 2019, the most common one needed was the replacement of the catalytic converter, which accounted for 5.69 percent of occurrences.

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That marks the first time in the report’s 10-year history that the emissions control device came out on top, with oxygen sensor replacement a close second at 5.67 percent and ignition coil/spark plugs issues third at 5.23 percent. CarMD says catalytic converters are one of the most robust components monitored by the "check engine" system, and that the issue has likely become more common because the average vehicle age has risen to 11.8 years.

THIS STATE HAS THE LOWEST CAR REPAIR COSTS

The average overall cost for a check engine light repair last year was $384, just a tick up from $380 in 2018. A typical catalytic converter replacement cost $1,375, while a broken or loose gas cap, number four on the list, was the cheapest fix, going for $25 to replace or just a twist of the wrist to close correctly.

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